Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
H,W=map(int, input().split())
S=[]
S.append(list(['X']*(W+2)))
for h in range(H):
    S.append(['X']+list(input())+['X'])
S.append(list(['X']*(W+2)))

from collections import deque
q=deque([[1,1]])
d=[(1,0),(-1,0),(0,1),(0,-1)]
S[1][1]=0

cnt_nm=0
for h in range(H+2):
    for w in range(W+2):
        if S[h][w]=='#':
            cnt_nm+=1

while q:
    y,x = q.popleft()
#     S[y][x]='X'
    for dy,dx in d:
        if S[y+dy][x+dx]=='.':
            q.append([y+dy,x+dx])
            S[y+dy][x+dx]=S[y][x]+1

if S[H][W]=='.':
    print('-1')
else:
    print(H*W-cnt_nm-S[H][W]-1)